1. Field of the Invention
The present invention relates generally to the diagnosis of pathologies of human lung tissues. More specifically, the present invention relates to the diagnosis of non-small cell lung cancers and asthma by measuring and quantifying expression levels of certain specific biomarkers present in human serum. More specifically, the present invention relates to the identification of biomarkers present in human serum, which, when altered in terms of expression levels from those found in a normal population, are indicative of pathologies associated with human lung tissues and the human respiratory system. By identifying the biomarkers associated with such pathologies, quantifying the expression levels of those biomarkers, and comparing the expression levels with those levels generally expected to present in a normal person's serum, it is possible to detect the presence of the pathologies early on in their progression through simple blood tests and to differentiate among the pathologies.
2. Description of the Related Art
Pathologies of the respiratory system, such as asthma and lung cancer, affect millions of Americans. In fact, the American Lung Association reports that almost 20 million Americans suffer from asthma. The American Cancer Society estimated 229,400 new cancer cases of the respiratory system and 164,840 deaths from cancers of the respiratory system in 2007 alone. While the five year survival rate of cancer cases when the cancer is detected while still localized is 46%, the five year survival rate of lung cancer patients is only 13%. Correspondingly, only 16% of lung cancers are discovered before the disease has spread. Lung cancers are generally categorized as two main types based on the pathology of the cancer cells. Each type is named for the types of cells that were transformed to become cancerous. Small cell lung cancers are derived from small cells in the human lung tissues, whereas non-small-cell lung cancers generally encompass all lung cancers that are not small-cell type. Non-small cell lung cancers are grouped together because the treatment is generally the same for all non-small-cell types. Together, non-small-cell lung cancers, or NSCLCs, make up about 75% of all lung cancers.
A major factor in the diminishing survival rate of lung cancer patients is the fact that lung cancer is difficult to diagnose early. Current methods of diagnosing lung cancer or identifying its existence in a human are restricted to taking X-rays, CT scans and similar tests of the lungs to physically determine the presence or absence of a tumor. Therefore, the diagnosis of lung cancer is often made only in response to symptoms which have presented for a significant period of time, and after the disease has been present in the human long enough to produce a physically detectable mass.
Similarly, current methods of detecting asthma are typically performed long after the presentation of symptoms such as recurrent wheezing, coughing, and chest tightness. Current methods of detecting asthma are typically restricted to lung function tests such as spirometry tests or challenge tests. Moreover, these tests are often ordered by the physician to be performed along with a multitude of other tests to rule out other pathologies or diseases such as chronic obstructive pulmonary disease (COPD), bronchitis, pneumonia, and congestive heart failure.
There does not exist in the prior art a simple, reliable method of diagnosing pathologies of human lung tissues early in their development. Furthermore, there is not a blood test available today which is capable of indicating the presence of a particular lung tissue pathology. It is therefore desirable to develop a method to determine the existence of lung cancers early in the disease progression. It is likewise desirable to develop a method to diagnose asthma and non-small cell lung cancer and to differentiate them from each other and from other lung diseases such as infections at the earliest appearance of symptoms. It is further desirable to identify specific biomarkers present in human blood which, when altered in terms of expression levels, are indicative of the presence of non-small cell lung cancers and/or asthma.